Purpose: This study was to investigate the effects of non-nutritive sucking on physiological and behavioral state of pre-term infants during tube feeding. Method: This nonequivalent, non-synchronized experimental study included 50 pre-term infants. An attempt was made to match gestational age and birth weight of infants in each group. Infants in the experimental group were given a pacifier 2 minutes before, during, and for 2 minutes after tube feeding. Infants in the control group did not get a pacifier. Both groups were tested at three stages for changes in the physiologic state and behavioral state - 2 minutes before, during, and 2 minutes after feeding. Date was analyzed with SPSS WIN 10.0 using an $X^2$-test, t-test, and repeated measures ANOVA. Result: Heart rates and oxygen saturation levels of the two groups were significantly different(P=.001, P=.000). The behavioral states of the two groups were significantly different during and post feeding(P=.000, P=.000). Conclusion: This result suggests non-nutritive sucking by using a pacifier is an effective intervention for pre-term infants during tube feeding.